System and method for position correction using power line carrier communications

ABSTRACT

The present invention provides a method for aligning spans using real-time kinetics (RTK) data communicated through a power line carrier system. According to a further preferred embodiment, the method of present invention includes the steps of: receiving a first set of GPS location data and second set of RTK data; comparing the first set of GPS location data with the second set of RTK data; calculating RTK error correction data; creating an RTK error correction data signal containing RTK error correction data; modulating the RTK error correction data signal for transmission on a power line carrier; transmitting the RTK error correction data signal through a power line BUS onto a power line to a last drive tower; de-modulating the RTK error correction data signal; calculating the location of the last drive tower using the RTK error correction data; calculating a straight, center line between the pivot and the last drive unit; calculating the relative distances between each intermediate drive tower and the calculated center line; and controlling the speed or average run time of each intermediate drive tower to reduce distance between their current locations and the calculated center line.

RELATED APPLICATIONS

The present application claims priority to U.S. Provisional ApplicationNo. 62/723,663 filed Aug. 28, 2018.

BACKGROUND AND FIELD OF THE PRESENT INVENTION Field of the PresentInvention

The present invention relates generally to a system and method forproviding correction and position signals to various powered elementswithin an irrigation machine to achieve a variety of objectives,including alignment control of irrigation spans, guidance of irrigationmachines (e.g. corners and linears) and to provide positionalinformation to a variety of remote monitoring and control devices.

Background of the Invention

Modern center pivot and linear irrigation systems generally includeinterconnected spans (e.g., irrigation spans) supported by one or moretower structures to support the conduits (e.g., water pipe sections). Inturn, the conduits are further attached to sprinkler/nozzle systemswhich spray water (or other applicants) in a desired pattern. In thesemodern irrigation systems, a significant number of powered elements areused to control various aspects of irrigation. These often include avariety of sensors, sprayers, drive control systems, motors andtransducers.

In the past, irrigation machines have utilized a variety of approachesto communicate data between system processors. These approaches haveincluded dedicated hard-wired systems (e.g. RS485, TCP/IP, RS232, etc.)and wireless systems (e.g. cellular, Wi-Fi, VHF/UHF radios, spreadspectrum radios and the like). Both of these solutions are costly andprone to communication errors. Hard-wired systems require theinstallation of significant lengths cable and wireless systems oftenrequire repeater stations to boost the radio signals over longdistances. Further, wireless systems have poor reliability due todistance, weather changes, obstacles, induced RF noise and longlatencies, particularly with cellular communications. Both systems havecaused errors in position reporting and have caused system delays due tofailed communications. The end result of these errors has been poorwater application uniformity, delays in application and other problemswhich have reduced yields and profitability for growers.

To overcome the limitations of the prior art, a reliable and effectivecommunication and control system is needed to control and alignirrigation spans and drive towers within a mechanized irrigation system.Further, a system is needed to provide guidance to steerable elements ofthe irrigation machine and to provide locational awareness of themachine (positional information) to a machine control system and toremote operators.

SUMMARY OF THE PRESENT INVENTION

To address the shortcomings presented in the prior art, the presentinvention provides a system for providing improved communications andlocational awareness within an irrigation system having at least onespan and a drive system for moving the spans.

According to a first preferred embodiment, the present inventionincludes a method for communicating Global Positioning System (GPS)location data throughout an irrigation system having a plurality ofconnected spans and a plurality of drive towers for moving the connectedspan around a center pivot having a pivot controller.

According to a second preferred embodiment, the present inventionincludes a method for communicating GPS Real Time Kinematic (RTK)correction signal data throughout an irrigation system having aplurality of connected spans and a plurality of drive towers for movingthe connected span around a center pivot having a pivot controller.

According to a further preferred embodiment, the system of the presentinvention preferably further includes a fixed RTK reference stationwhich calculates GPS location errors and transmits the error correctiondata using modulated signals transmitted through a power line carrier(PLC) system to one or more downstream GPS units providing guidance toan irrigation machine such as the said roving GPS unit.

According to a further preferred embodiment, a method of presentinvention includes the steps of: at a fixed (reference) station,receiving a first set of GPS location data and second set of RTK data;comparing the first set of GPS location data with the second set of RTKdata; calculating RTK error correction data; creating an RTK errorcorrection data signal containing RTK error correction data; modulatingthe RTK error correction data signal for transmission on a power linecarrier; broadcasting the RTK error correction data signal through apower line BUS onto a power line to a last drive tower; at a mobile(rover) station, receiving said error correction data signal through apower line BUS; de-modulating the RTK error correction data signal;calculating the location of the mobile station using the RTK errorcorrection data

According to a further preferred embodiment, a last regular drive unit(LRDU) or corner drive tower may preferably include a GPS receiving unitwhich preferably acts as a mobile (rover) GPS unit providing a guidancesignal to the corner drive tower or LRDU.

According to a further preferred embodiment, the error correction datatransmitted to the downstream mobile (rover) GPS units at each driveunite may also be used to maintain alignment of the irrigation machinecomponents (e.g. irrigation spans)

According to a further preferred embodiment, alignment may be maintainedby calculating a straight, center line between the pivot and the lastregular drive unit; calculating the relative distances between eachintermediate drive tower and the calculated center line; and controllingthe speed or average run time of each intermediate drive tower to reducedistance between their current locations and the calculated center line.

According to a further preferred embodiment, the GPS units of thepresent invention may preferably further transmit GPS location data(including Wide Area Augmentation System corrected data) to a centralcontrol panel, typically located at the center pivot point or linearcart. According to a further preferred embodiment, the location data ofthe present invention may preferably be utilized for a variety ofapplications, such as turning the end-gun sprinkler on or off as acenter pivot moves through areas of the field where water beyond the endof the structure is, or is not, required; transmitting irrigationmachine location to the cloud for remote monitoring and control of saidmachine, such as reporting of location of machine within the field; andfor a variety of other needs, both locally at the irrigation machine orremotely (in the cloud or for a remote operator).

According to a further preferred embodiment, a method of presentinvention may include the steps of: receiving a first set of GPSlocation data; modulating the GPS location data signal for transmissionon a power line carrier; broadcasting the GPS location data signalthrough a power line BUS onto a power line to a plurality of drivetowers and a central control unit; de-modulating the GPS location datasignal at each drive tower and central control unit and making said GPSlocation data available for use at said drive towers and central controlunit.

According to a further preferred embodiment, all GPS units on the PLCsystem may transmit their locational data for use by other GPS units fora variety of reasons, such as comparing relative positions betweenspans, calculation of relative angles between spans, relative elevationsbetween drive units and the rates of change of said angles andelevations and the like.

The accompanying drawings, which are incorporated in and constitute partof the specification, illustrate various embodiments of the presentinvention and together with the description, serve to explain theprinciples of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows an exemplary irrigation system for use with the presentinvention.

FIG. 2 shows a block diagram illustrating the exemplary processingarchitecture of a control device in according with a first preferredembodiment of the present invention.

FIG. 3 shows an irrigation system in accordance with further preferredembodiment of the present invention.

FIG. 4 shows a block diagram in accordance with further preferredembodiment of the present invention.

FIG. 5 shows a flow chart illustrating an exemplary method in accordancewith a first preferred embodiment of the present invention.

FIG. 6 provides a flow chart illustrating an exemplary method inaccordance with a first preferred embodiment of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

For the purposes of promoting an understanding of the principles of thepresent invention, reference will now be made to the embodimentsillustrated in the drawings and specific language will be used todescribe the same. It will nevertheless be understood that no limitationof the scope of the present invention is hereby intended and suchalterations and further modifications in the illustrated devices arecontemplated as would normally occur to one skilled in the art.

In accordance with preferred embodiments of the present invention, itshould be understood that the term “drive unit” may preferably include anumber of sub-components including: a motor, a controller, acommunication device (such as a PLC or the like) and an alignmentdevice. Further, while the invention is discussed below with respect tofour exemplary towers, the number of towers used may be expanded orreduced (i.e. 1-100 towers) as needed without departing from the spiritof the present invention. Further, the term “motor” as used herein mayrefer to any suitable motor for providing torque to a drive wheel.Accordingly, the term “motor” as used herein may preferably includemotors such as switch reluctance motors, induction motors and the like.

The terms “program,” “computer program,” “software application,”“module,” firmware” and the like as used herein, are defined as asequence of instructions designed for execution on a computer system.The term “solid state” should be understood to refer to a range of solidstate electronic devices which preferably include circuits or devicesbuilt from solid materials and in which the electrons, or other chargecarriers, are confined entirely within the solid material. Exemplarysolid-state components/materials may include crystalline,polycrystalline and amorphous solids, electrical conductors andsemiconductors. Common solid-state devices may include transistors,microprocessor chips, and RAM.

A program, computer program, module or software application may includea subroutine, a function, a procedure, an object implementation, anexecutable application, an applet, a servlet, a source code, an objectcode, a shared library, a dynamic load library and/or other sequence ofinstructions designed for execution on a computer system. A data storagemeans, as defined herein, includes many different types of computerreadable media that allow a computer to read data therefrom and thatmaintain the data stored for the computer to be able to read the dataagain. Such data storage means can include, for example, non-volatilememory, such as ROM, Flash memory, battery backed-up RAM, Disk drivememory, CD-ROM, DVD, and other permanent storage media. However, evenvolatile storage such a RAM, buffers, cache memory, and network circuitsare contemplated to serve as such data storage means according todifferent embodiments of the present invention.

Aspects of the systems and methods described herein may be implementedas functionality programmed into any of a variety of circuitry,including programmable logic devices (PLDs), such as field programmablegate arrays (FPGAs), programmable array logic (PAL) devices,electrically programmable logic and memory devices and standardcell-based devices, as well as application specific integrated circuits(ASICs). Some other possibilities for implementing aspects of thesystems and methods includes: microcontrollers with memory, embeddedmicroprocessors, firmware, software, etc. Furthermore, aspects of thesystems and methods may be embodied in microprocessors havingsoftware-based circuit emulation, discrete logic (sequential andcombinatorial), custom devices, fuzzy (neutral network) logic, quantumdevices, and hybrids of any of the above device types. Of course, theunderlying device technologies may be provided in a variety of componenttypes, e.g., metal-oxide semiconductor field-effect transistor (MOSFET)technologies like complementary metal-oxide semiconductor (CMOS),bipolar technologies like emitter-coupled logic (ECL), polymertechnologies (e.g., silicon-conjugated polymer and metal-conjugatedpolymer-metal structure), bidirectional triode thyristors (TRIAC), mixedanalog and digital, and the like.

As shown in FIG. 1, the exemplary system 100 shown includes a span 101which preferably includes a series of connected span sections which maybe pressurized to facilitate the transfer of water from a water sourcethrough the irrigation system 100. The fluid source may be coupled to arepository or other source of agricultural products to injectfertilizers, pesticides, and/or other chemicals into the fluids tocreate an applicant for application during irrigation. Thus, theapplicant may be water, fertilizer, herbicide, pesticide, combinationsthereof, or the like. The exemplary system 100 may further include amain control panel 102 which may control transducers, sensors and valves(not shown) to control and regulate water pressure to sprinklers (notshown) including an end gun 136 and other sprinkler heads (not shown).

As further shown, the system may include drive towers 104, 106, 108, 110having respective tower control boxes 120, 122, 124, 126. As furthershown, these tower control boxes may be interfaced with respectivealignment sensors 128, 130, 132, 134 and control respective drive unitmotors 112, 114, 116, 118. As discussed above, the system of the presentinvention may include any motor suitable for providing torque to a drivewheel or wheels. According to a preferred embodiment, the system of thepresent invention may preferably include motors such as switchreluctance motors, induction motors and the like.

With reference now to FIG. 2, an exemplary control device 138 whichrepresents functionality to control one or more operational aspects ofthe irrigation system 100 will now be discussed. As shown, an exemplarycontrol device 138 preferably includes a processor 140, a memory 142, adata storage module 150 and a network interface 144. The processor 140provides processing functionality for the control device 138 and mayinclude any number of processors, micro-controllers, or other processingsystems. The processor 140 may execute one or more software programsthat implement techniques described herein. The memory 142 is an exampleof tangible computer-readable media that provides storage functionalityto store various data associated with the operation of the controldevice 138, such as the software program and code segments mentionedabove, or other data to instruct the processor 140 and other elements ofthe control device 138 to perform the steps described herein. The memory142 may include, for example, removable and non-removable memoryelements such as RAM, ROM, Flash (e.g., SD Card, mini-SD card, micro-SDCard), magnetic, optical, USB memory devices, and so forth. The networkinterface 144 provides functionality to enable the control device 138 tocommunicate with one or more networks 149 through a variety ofcomponents such as wireless access points, transceivers and so forth,and any associated software employed by these components (e.g., drivers,configuration software, and so on). As shown, a preferred system of thepresent invention may include a satellite transceiver 159 or the likefor receiving direct satellite communications.

In implementations, exemplary control device 138 preferably furtherincludes a power control system 145, a power line control (PLC) board146 and a power-line BUS 147. According to a preferred embodiment of thepresent invention, the power-line BUS 147 preferably may includeconductive transmission lines, circuits and the like for controlling androuting electric power, controlling its quality, and controlling thedevices attached to a power-line carrier system as discussed furtherbelow. According to further preferred embodiments, the PLC board 146preferably routes and converts power and data signals which aretransmitted through the power-line BUS 147 as discussed further below.

Further, the system of the present invention preferably may furtherinclude an irrigation position-determining module 148 which may furtherinclude a global positioning system (GPS) receiver 157 or the like tocalculate a location of the irrigation system 100. In accordance with afurther preferred embodiment of the present invention, the irrigationposition determining module 148 preferably further includes a real-timekinematics (RTK) Error Calculation Module 155 as discussed furtherbelow. According to preferred embodiments, the processing of RTK signalsas discussed herein may preferably be conducted using a single frequencyor dual frequencies without limitation.

As further shown, control device 138 may be coupled to a guidance deviceor similar system 152 of the irrigation system 100 (e.g., steeringassembly or steering mechanism) to control movement of the irrigationsystem 100 and to assist in controlling the movement and locationalawareness of the system. Further, the control device 138 may preferablyfurther include multiple inputs and outputs to receive data from sensors154 and monitoring devices as discussed further below.

According to a preferred embodiment, the RTK Error Calculation Module155 preferably functions to perform RTK error calculations to enhancethe precision of position data derived from the GPS system 157. Althoughthe present invention is discussed with respect to GPS, the presentinvention applies to data received from other positioning systems suchas LORAN, GLONASS, Galileo, BeiDou and the like, as well as anycombination of those like systems. Additionally, RTK can utilize asingle frequency (commonly known as the L1 band) for corrections or canutilize dual frequencies (commonly known as the L1 and L2 bands).Further like correction technologies (such as WAAS, or Differential GPS)that enhance positional accuracy may be used. Preferably, any suchsystems would be compatible with the like positioning systems discussedabove and provide positional accuracy better than 1 meter.

With reference now to FIG. 3, an exemplary system 300 incorporatingaspects of the present invention shall now be further discussed. Asfurther shown, an exemplary irrigation system 300 may includetransducers (not shown) which are provided to control and regulate waterpressure to sprinklers including the end gun 321 and other sprinklerheads 326.

Further the system may preferably include solid state tower boxes 312,314, 316 (including the PLC boards, solid-state motor controllers,non-contact alignment devices and other components as discussed aboveand further with respect to FIG. 4 below) which are preferablyinterconnected to respective drive unit motors 307, 309, 311. As furthershown, the respective drive unit motors 307, 309, 311 preferably providetorque and braking to respective sets of drive wheels 302, 304, 306. Asdiscussed above, the system of the present invention may include anysuitable motor for providing torque to a drive wheel. According to apreferred embodiment, the system of the present invention may preferablyinclude motors such switch reluctance motors, induction motors and thelike.

Further, the system 300 of the present invention may preferably furtherinclude a control/pivot panel 308 as well as elements such as a GPSreceivers 320 a-d for receiving positional data. Still further, a systemof the present invention may further include indirect crop sensors 318,322 which preferably may include optional moisture sensors to determinethe moisture levels in a given area of soil. Additionally, the sensors318, 322 may further include optics to allow for the detection of croptype, stage of grown, health, presence of disease, rate of growth andthe like. Still further, the system may include ground sensors. Stillfurther, the detection system may further receive data from a connectedor remote weather station or the like which is able to measure weatherfeatures such as humidity, wind speed, wind direction, pressure,precipitation, temperature and the like. Further, the preferred systemof the present invention may alternatively further include additionalelements mounted to the span 310 such as additional sensors and thelike.

As further shown in FIG. 3 and as discussed further below, a preferredsystem of the present invention may further include a Real TimeKinematic (RTK) reference station 328 for providing error correctiondata to a GPS roving receiver which may be attached to a corner drivetower 325 or the like as discussed further below. Preferably, the RTKreference station 328 is positioned on a very accurately surveyed point.Still further, the RTK reference station 328 preferably receives GPSsignals and calculates error correction data based on the locationdifferences between the surveyed location and the location dataindicated by the measured GPS signals. According to a further preferredembodiment, a last regular drive unit (LRDU), corner drive tower or cartmay preferably include a GPS receiving unit 320 d which preferably actsas a roving GPS unit.

With reference now to FIG. 4, once the RTK reference station 403 (aloneand/or in combination with the pivot controller 410 and the RTK ErrorCalculation Module 155), creates error correction data, the errorcorrection data is then preferably transmitted by the pivot controller410 as an error correction data signal to the pivot point PLC board 414.The pivot point PLC board 414 then preferably modulates the errorcorrection data signal and transmits the signal through the power lineBUS 416 and PLC system to one or more downstream GPS units/controllers405, 407, 409. In this way, each receiving GPS unit/controller of thepresent invention receives enhanced RTK guidance. According to a furtherpreferred embodiment, the GPS units/controllers 405, 407, 409 of thepresent invention may further transmit GPS location data to the pivotcontroller 410 to provide additional locational awareness.

According to a further preferred embodiment, the RTK reference station403 may preferably be located within a collector ring/slip ring device411 attached to the center pivot point. According to alternativepreferred embodiments, the location (longitude, latitude) of the RTKreference station may be set by any method known in the art. Forexample, the RTK reference station location may be manually set by userinput from data gathered outside the system. Alternatively, the RTKreference station location may be set via a “survey mode” where thelocation of the unit is determined using known algorithms totime-average GPS positional data gathered by the receiver.

With further reference now to FIG. 4, the power/control system of thepresent invention 400 may preferably include a control/pivot panel box402 which preferably provides control signals and power to a series ofintermediate solid-state tower boxes 404, 406 and a last regular driveunit (LRDU)/cart/rover tower box 408. As shown, each solid-state towerbox 404, 406, 408 preferably further includes a GPS sensor/input 405,407, 409. It should be understood that solid-state tower boxes areprovided as an example and the present invention is not intended to belimited to the use of solid-state tower boxes. For example,electro-mechanical tower boxes may be used with the PLC system of thepresent invention in place of the solid-state tower boxes withoutdeparting from the scope of the present invention.

As further shown, the control/pivot panel box 402 of the presentinvention may preferably include a main pivot controller 410 connectedto a pivot point PLC board 414 which controls and directs power todownstream intermediate solid-state tower boxes 404, 406 and cornerdrive tower/cart/rover tower box 408. According to a preferredembodiment, the pivot controller 410 may be directly wired to the pivotpoint PLC board 414 or connected via a serial communication connection412 (i.e. RS-232) or the like. According to preferred embodiments, thepivot panel box 402 preferably provides power and control signalsthrough the pivot point PLC board 414 to the downstream solid-statetower boxes 404, 406, 408 via a power-line BUS 416.

According to preferred embodiments, the power-line BUS 416 of thepresent invention may provide and direct power at any of a variety ofdifferent voltages and amps. For example, the power-line BUS 416 of thepresent invention may provide power over a range of voltages (such asbetween 0-1000 volts) and over a range of currents (such as 0.1 to 100amps) as desired without limitation. According to a further preferredembodiment, the power may be provided at 120-480 volts with a currentanywhere between 5-50 amps. For instance, the power-line BUS 416 mayprovide 120 volts AC at 5 amps. According to a further preferredembodiment, the power-line BUS 416 may preferably provide power at 480volts AC at 30 amps. According to a further preferred embodiment, thepower-line carrier of present invention may preferably operate as a oneor two-way system.

As further shown in FIG. 4, the RTK data is preferably first received bythe RTK reference station 403 which may be located within a collectorring 411 attached to the riser. Thereafter, the data is provided to theRTK Error Calculation Module 155 to calculate and produce GPS errorcorrection data. Thereafter, the RTK Error Calculation module 155preferably transmits the RTK error correction data to the pivot pointPLC board 414 where the signal is modulated and transmitted (along withpower and control signals provided by the power-line box 416) to thedownstream solid-state tower boxes 404, 406, 408 and pivot controller410 via a power-line BUS 416.

The error correction data signal is preferably first received by a firstintermediate solid-state tower box 404 which preferably receives,processes and thereafter directs the received power to a center drivemotor 418. Further, the RTK error correction data is preferably furtherprocessed by the intermediate solid-state tower box 404 and used tocorrect/adjust the GPS location data received from the GPS module 405.Thereafter, the power and control signals may be further transmitted toone or more downstream tower boxes 406 which likewise process thereceived signals. Although not shown, any number of additionalintermediate solid-state our boxes may be incorporated as neededdepending on the size of the irrigation system. Regardless of the numberof intermediate solid-state tower boxes, the RTK error correction dataand the power from the power-line bus 416 are preferably finallyreceived at a corner drive tower box 408 which preferably likewisereceives and processes the received RTK error correction data as well asdirects the received power to a center drive motor 422.

As further shown in FIG. 4, the corner drive tower box 408 maypreferably further include a GPS guidance control (GC) panel 413 forreceiving and processing guidance control signals. Still further, thecorner drive tower box 408 may preferably further include a PLC board419 for receiving/transmitting and translating control and power signalsbetween the tower box control panel 415 and the other systemscommunicating through the power-line BUS 416 as discussed further below.Further, each tower box 404, 406 may preferably further include similarPLC boards (not shown) to provide similar functions.

In operation, the GC system 413 mounted on the end of the irrigationmachine may preferably receive signals from GPS satellites via a GPSsensor 409 or the like and calculate the position of the unit. Asdiscussed above, such calculations may include data from a Wide AreaAugmentation System (WAAS) or the like. This data may then betransmitted to the PLC board 419 via a conventional wired connection ofany type (including being integrated onto the same circuit board as theGPS receiver). Thereafter, the PLC board 419 may then preferablytransmit the GPS position data to the pivot point PLC board 414 whichmay demodulate and send the signals to the main pivot controller 410where the data may be used to indicate the position (i.e. distance,compass angle etc.) of the irrigation machine relative to the pivotpoint. The pivot controller 410 may then further report the positiondata via a communications system to a cloud-based remote monitoring andcontrol system to allow a remote operator to know the position of theirrigation machine within the field. Further, the pivot controller 410may use the positional data to activate or deactivate auxiliarysprinklers based on the location of the irrigation machine. Stillfurther, the pivot controller 410 may use the positional data to adjustthe speed of the machine and/or pulsing rate of sprinklers to complywith a variable rate irrigation prescription as discussed further below.Still further, the pivot controller 410 may use the positional data tomake further calculations such as calculating slip rate or the like todetect a stuck machine.

With reference now to FIGS. 4 and 5, a preferred method 500 inaccordance with preferred embodiments of the present invention shall nowbe discussed. According to a first preferred embodiment, at a first step502, GPS position data are preferably first received by the fixed(reference) station 403. Alternatively, this data may be input frommemory or received from an outside network. According to a preferredembodiment, the GPS data are compared to the reference geographiclocation stored in the fixed (reference) station. Thereafter, at a nextstep 504, stored geographic data and GPS data are then preferablyprocessed by the RTK Error Calculation Module 155 of the PLC board 414to create RTK error correction data. At a next step 505, the pivot pointPLC board 414 then preferably modulates the error correction data into adata signal that can be transmitted through the power line BUS 416.

At a next step 507, the RTK error correction data is preferablytransmitted to each downstream drive tower controller 404, 406, and 408.Preferably, the data signals are transmitted through the power-line BUS416 to one or more receiving PLC boards within the downstream towerboxes 404, 406, 408. According to a preferred embodiment, an LRDU PLCboard 419 may receive the correction data and demodulate the receiveddata signal. Thereafter, the PLC board 419 may preferably forward thecorrection data to the corner drive tower box controller 415 and/or GCpanel 413 to use in location refinement and other calculations.According to a preferred embodiment, the frequency of the corrected datatransmission may be once per second. Alternatively, the corrected datamay be transmitted at faster or slower intervals.

At a next step 508, the location of the corner drive tower 408 maypreferably be calculated using GPS data and RTK error correction data.At a next step 510, the corner drive tower 408 may preferably calculatedistance adjustments (preferably using a deviation error or pathprojection algorithm or the like) and make adjustments to drive speedand/or directions to correct the drive tower location relative to theprescribed drive tower location. For example, the controllers for eachdrive tower may control their drive wheels to reduce distance betweentheir current locations and a desired guidance path. This may preferablybe accomplished by adjusting the duty cycle of a start-stop motor, byincreasing or reducing the RPM of a variable speed motor (such as aswitch reluctance motor or an induction motor driven by a variablefrequency drive) or by like methods.

According to an alternative preferred embodiment, each individual drivetower may increase or reduce its speed to reduce the distance betweenitself and a center line calculated between the pivot point to the lastdrive tower in order to maintain substantially straight alignment of thenon-corner irrigation spans. Preferably, any such the calculationsand/or adjustments by the drive towers of the present invention may becontinually performed in real time to maintain alignment duringirrigation. Additionally, the RTK correction signal may preferably besent out in real-time to allow each tower controller to correct GPSerrors in real-time.

According to an alternative preferred embodiment, the speed of a drivewheel may be controlled by adjusting or changing the programmed averagespeed of the drive wheel. The present invention may thus continuallyupdate the programmed average speed of each tower as necessary and maycontinually cycle between location detection and updating of programmedaverage speeds of each tower to minimize the misalignment of towers.

According to further preferred embodiments, the alignment algorithms ofthe present invention may operate when the machine is still or duringthe running of the irrigation system. Further, the algorithms andsystems of the present invention may be used to initially align thetowers every time the machine is started (i.e., at the beginning of themachine movement) rather than during machine movement. According to afurther preferred embodiment, the algorithm of the present invention maypreferably include a margin error so that only towers located more thana set distance (i.e. two inches) from a given centerline are instructedto reduce detected alignment errors. According to a further preferredembodiment, the order of alignment may be determined in the order of theoutermost tower to the innermost tower. Further, the instructions forrealigning the towers may be prioritized from the outermost tower to theinnermost tower.

With reference now to FIGS. 4 and 6, an alternative alignment method 600for use with the present invention shall now be discussed. According toan exemplary alternative algorithm, at a preferred first step 602, thepivot controller 410 of the present invention preferably receives afirst set of GPS location data. According to a preferred embodiment, theGPS data may be received directly by GPS satellite receivers.Alternatively, this data may be input from memory or received from anoutside network.

At a next step 604, the pivot controller 410 preferably compares the GPSlocation data with the reference geographic location stored in the fixed(reference) station. At a next step 606, the pivot controller 410preferably calculates RTK error correction data. At a next step 608, theRTK error correction data is preferably transmitted to each downstreamdrive tower controller 404, 406, 408 via the power line carrier network.

At next step 610, each tower control unit may preferably broadcastcorrected position data to adjacent drive tower controllers. Accordingto a preferred embodiment, each tower control unit may transmitcorrected position data via a connected PLC board. According toalternative preferred embodiments, the corrected position data may betransmitted directly between drive tower controllers or may first betransmitted to the central pivot point controller 410 which may thenstore and transmit location data to each drive controller through thePLC BUS 416. At a next step 612, each pair of adjacent towers maypreferably calculate a straight, center line between themselves usingthe corrected position data. At a next step 614, the drive towers maycalculate their relative distances to the calculated center line. At anext step 616, the controller for each drive tower may then control aset of drive wheels to reduce distance between their current locationand the calculated center line. For example, a motor may preferably becontrolled to increase its speed so that the distance between itself andthe center line is reduced while the irrigation machine travels in agiven direction thus reducing the angular offset between drive towers.

Preferably, multiple groups of towers may act simultaneously to alignthemselves and to continually updated center lines. For example, thesystem may preferably analyze and align multiple three tower groups atthe same time. Further, the “three-tower alignment” may preferably berun at every tower along the machine, beginning with the tower closestto the end tower and proceeding inward. The alignment may preferably berun simultaneously amongst all the towers. Additionally, the pivotcontroller 410 may preferably continually send out real-time kinematics(RTK) signals to all of the downstream towers to allow each towercontroller to correct GPS errors and calculate correction location data.

According to a further preferred embodiment, all the towers may becontinuously aligned until all the “delta” lengths are within a certainthreshold for alignment. During the alignment process, the end tower maypreferably be moving to minimize stress on the span. According tofurther aspects of the present invention, it should be understood thatthe use of groups of three towers as discussed above is provided as apreferred example only. Alternatively, any other number of towers may beused as a group as well.

According to alternative embodiments, the present invention may utilizeanalog sensors on each tower. For example, a LORAN device could belocated on each tower and the system may then, for example, utilize thethree-tower alignment algorithm in conjunction with the triangulationdata from the LORAN devices. Further, LORAN could also be utilized as abackup to the GPS sensors, in case the GPS sensors failed or becameunavailable.

According to a further preferred embodiment, the GPS sensor of thepresent invention may preferably be placed as low to the ground aspossible. Further, where a GPS sensor needs to be placed higher on atower, any resulting terrain-caused tracking error may preferably becorrected or compensated for by utilizing an inclinometer and/orgyroscope sensor data for the GPS sensor at the tower. In this case, theGPS coordinates reported by the sensor may be adjusted based on theamount of tilt in the tower (due to terrain slopes) as measured by aco-mounted inclinometer and/or gyroscope sensor. Alternatively, if theGPS sensor is mounted closer to the pipe on the tower, then there is noneed to compensate for terrain-induced tilt.

While the above descriptions regarding the present invention containmuch specificity, these should not be construed as limitations on thescope, but rather as examples. Many other variations are possible. Forexample, the processing elements of the present invention by the presentinvention may operate on a number of different frequencies, voltages,amps and BUS configurations. Further, the communications provided withthe present invention may be designed to be duplex or simplex in nature.Further, the systems of the present invention may be used with anyarrangement of drive towers including both linear and center pivotsystems. Further, as needs require, the processes for transmitting datato and from the present invention may be designed to be push or pull innature. Still, further, each feature of the present invention may bemade to be remotely activated and accessed from distant monitoringstations. Accordingly, data may preferably be uploaded to and downloadedfrom the present invention as needed.

Accordingly, the scope of the present invention should be determined notby the embodiments illustrated, but by the appended claims and theirlegal equivalents.

What is claimed is:
 1. A method for aligning spans using real-timekinetics (RTK) data communicated through a power line carrier system,wherein the system comprises a plurality of connected spans and aplurality of drive towers for moving the connected span around a centerpivot having a pivot controller; wherein each drive tower is comprisedof a power line carrier node; further wherein the drive towers includeintermediate drive towers and a last drive tower, further wherein thesystem comprises a fixed reference station storing reference locationdata; wherein the method comprises: receiving a first set of GPSlocation data; comparing the first set of GPS location data with thereference location data stored in the fixed reference station;calculating RTK error correction data; creating an RTK error correctiondata signal; modulating the RTK error correction data signal fortransmission on a power line carrier; wherein the power-line carrier iscomprised of a plurality of electrically conductive elements which areconfigured to connect and deliver signals to and from a power-line BUS;transmitting the RTK error correction data signal through the power lineBUS onto the power line to the power line carrier node of each drivetower; de-modulating the RTK error correction data signal; calculatingthe location of the last drive tower using the RTK error correctiondata; calculating a center line between the pivot and the last driveunit; calculating the relative distances between each intermediate drivetower and the calculated center line; wherein the distance calculationis made using a linear regression algorithm; and controlling the speedof each intermediate drive tower to reduce distance between theircurrent locations and the calculated center line.
 2. The method of claim1, wherein the first set of GPS location data is input from memory;further wherein the speed of each intermediate drive tower is controlledby reducing the average run time of each intermediate drive tower.
 3. Ina system comprising a plurality of connected spans and a plurality ofdrive towers for moving the connected span around a center pivot havinga pivot controller; wherein the plurality of drive towers includes afirst drive tower, a last drive tower and a corner drive tower; whereineach of the plurality of drive towers comprises a tower controller andpower line carrier node; further wherein the system comprises a fixedreference station for storing reference location data, the methodcomprising: receiving a first set of GPS location data; comparing thefirst set of GPS location data with reference location data stored inthe fixed reference station; calculating RTK error correction data;wherein the RTK error correction data is calculated using at least thefirst set of GPS location data and the reference location data; creatingan RTK error correction data signal, wherein the RTK error correctiondata signal comprises RTK error correction data; modulating the RTKerror correction data signal for transmission on a power line carrier;wherein the power-line carrier is comprised of a plurality ofelectrically conductive elements which are configured to connect anddeliver signals to and from a power-line BUS via a power line;transmitting the RTK error correction data signal through the power lineBUS onto the power line to the power line carrier node of each drivetower; de-modulating the RTK error correction data signal at the cornerdrive tower; calculating the location of the corner drive tower usingthe RTK error correction data; comparing the calculated location of thecorner drive tower to a target location for the corner drive tower;wherein the step of comparing comprises calculating a distance betweenthe calculated location of the corner drive tower and the targetlocation of the corner drive tower; wherein the distance calculation ismade using a linear regression algorithm; and controlling the speed ofthe corner drive unit to reduce the distance between the calculatedlocation and the target location of the corner drive unit.
 4. The methodof claim 3, wherein the calculation is performed using a deviation erroralgorithm.
 5. The method of claim 4, wherein the calculation isperformed using a path projection algorithm.
 6. The method of claim 5,wherein the distance between the calculated location and the targetlocation of the corner drive unit is reduced by adjusting the duty cycleof a start-stop motor.
 7. The method of claim 6, wherein the distancebetween the calculated location and the target location of the cornerdrive unit is reduced by changing the RPM of a variable speed motor. 8.The method of claim 7, wherein the RTK correction signal is transmittedin near-real-time to allow each tower controller to correct GPS errorsin real-time.
 9. The method of claim 8, wherein the distance between thecalculated location and the target location of the corner drive unit isreduced by changing the programmed average speed of a drive tower drivewheel.
 10. The method of claim 9, wherein distance corrections areperformed in order of the outermost tower to the innermost tower.
 11. Inan irrigation system which includes a plurality of connected spans and aplurality of drive towers for moving the connected span around a centerpivot having a pivot controller, an irrigation control system, theirrigation control system comprising: a tower control panel, wherein thetower control panel comprises a first PLC board; an RTK referencestation, wherein the RTK reference station is configured to receive RTKdata; wherein the RTK reference station is located within a collectorring attached to a riser of the center pivot; an RTK Error CalculationModule, wherein the RTK Error Calculation Module is configured toreceive the RTK data and to produce GPS error correction data; whereinthe RTK Error Calculation module is configured to transmit the GPS errorcorrection data to the first PLC board; wherein the first PLC board isconfigured to modulate and transmit an RTK error signal comprising theGPS error correction data; wherein the first pivot point PLC board isconfigured to output power and control signals to a plurality ofdownstream solid-state tower boxes; a first tower box, wherein the firsttower box is a solid-state tower box configured to control theoperations of a first drive tower, wherein the first tower box isconfigured to receive the RTK error signal, power and control signalsfrom the first PLC board; wherein the first tower box is configured todirect the received power to a first tower drive motor; a second towerbox, wherein the second tower box is a solid-state tower box configuredto control the operations of a second drive tower, wherein the secondtower box is configured to receive the RTK error signal, power andcontrol signals from the first PLC board; wherein the second tower boxis configured to direct the received power to a second tower drivemotor; a corner tower box, wherein the corner tower box is a solid-statetower box configured to control the operations of a corner drive tower,wherein the corner tower box is configured to receive the RTK errorsignal, power and control signals from the first PLC board; wherein thecorner tower box is configured to direct the received power to a cornertower drive motor; wherein the corner tower box comprises a second PLCboard and a guidance control panel; wherein the second PLC board isconfigured to receive power and control signals from the first PLCboard; wherein the guidance control panel is configured to receive GPSsensor data and the RTK error signal; wherein the second PLC board isconfigured to generate corner tower position data using the RTK errorsignal; wherein the second PLC board is configured to transmit thecorner tower position data to the first PLC board.
 12. The system ofclaim 11, wherein the position of the irrigation machine is calculatedat least in part using data from a Wide Area Augmentation System (WAAS).13. The system of claim 12, wherein the pivot controller is configuredto transmit the corner tower position data to a remote cloud-basedmonitoring and control system.
 14. The system of claim 13, wherein thepivot controller is configured to use the corner tower position data tocontrol one or more sprinklers based on the location of the irrigationmachine.
 15. The system of claim 14, wherein the pivot controller isconfigured to use the corner tower position data to adjust the speed ofthe machine.
 16. The system of claim 15, wherein the pivot controller isconfigured to use corner tower position data to control the pulsing rateof sprinklers to comply with a variable rate irrigation prescription.17. The system of claim 16, wherein the pivot controller is configuredto use the corner tower position data to calculate the slippage rate ofa drive tower.
 18. The system of claim 17, wherein the system furthercomprises: a third tower box, wherein the third tower box is asolid-state tower box configured to control the operations of a thirddrive tower, wherein the third tower box is configured to receive theRTK error signal, power and the control signals from the first PLCboard; wherein the third tower box is configured to direct the receivedpower to a third tower drive motor; wherein the first, second, third andcorner drive towers are configurable to transmit and receive correctedposition data from one or more adjacent drive towers; wherein the firstand second driver towers are adjacent; wherein the second and thirddrive towers are adjacent; wherein the third drive tower and the cornerdrive tower are adjacent; wherein a first pair of adjacent drive towersare configured to independently calculate the distance to a center linebetween the first pair of adjacent drive towers using location datacorrected using the RTK error signal; wherein the first pair of adjacenttowers are configured to assign only one of the two adjacent drive towerboxes to control a set of drive wheels to reduce distance between acurrent location and the calculated center line.
 19. The system of claim18, wherein the system further comprises a plurality of alignmentgroups; wherein a first alignment group is comprised of a pluralitydriver towers; wherein the first alignment group is configured tocoordinate the alignment of the plurality drive towers within the firstalignment group independent of instructions from the tower controlpanel.
 20. The system of claim 19, wherein the first alignment group iscomprised of three drive towers; wherein the first alignment group isconfigured to transmit alignment data among the first alignment grouptower boxes; wherein the first alignment group is configured to aligneach of the three drive towers along a centerline calculated by thefirst alignment group tower boxes.
 21. The system of claim 20, whereinthe plurality of alignment groups are configured to align in sequencebased on their distances from the center pivot.
 22. The system of claim21, wherein alignment groups furthest from the center pivot areconfigured to align before alignment groups closest to the center pivot.